eprintid: 1571169 rev_number: 25 eprint_status: archive userid: 608 dir: disk0/01/57/11/69 datestamp: 2017-11-10 12:36:20 lastmod: 2020-02-12 16:15:31 status_changed: 2017-11-10 12:36:20 type: thesis metadata_visibility: show creators_name: Virdee, Hira Singh title: Radiation pressure torque and computational attitude modelling of space debris ispublished: unpub divisions: UCL divisions: A01 divisions: B04 divisions: C05 keywords: Space debris, computational attitude modelling, attitude modelling, torque modelling, force modelling abstract: Human space activity in the past 50 years has led to a plethora of man-made space debris which pose an imminent threat to global space operations. The current models of space debris orbits are not sufficient for detailed orbit prediction or for accurate tracking. This uncertainty manifests itself in Conjunction Analysis (CA) with active spacecraft, which leads to excessive orbital manoeuvres which are both expensive and reduce the lifetime of satellites. Advances in orbit modelling will lead to better prediction of debris orbits and reduce the need for collision avoidance manoeuvres, as well as minimising the future pollution of the space environment through collisions. Most existing methods for analysing the orbits of space debris do not take into account the effects of tumbling, and the attitude-dependent nonconservative forces are generally neglected. This study models the torques and attitude motion of uncontrolled man-made objects in orbit about the Earth, which tumble due to a combination of natural influences of the near-Earth space environment and initial angular momentum acquired during debris formation. The modelling of space debris is a relatively new field and represents a huge new area of research. The two main branches of this thesis are (a) modelling the torques that induce spin for objects in orbit, and (b) modelling the effect of certain attitude-dependent non-conservative forces on spinning objects in orbit. The main torque modelled in this study is solar radiation pressure (SRP). Simulations of the radiation-induced torques are performed and the main mechanisms that lead to the tumbling of uncontrolled objects are analysed. A novel method of presenting attitude-dependent forces and torques on space objects, dubbed ”Torque Maps”, is presented. Radiation torques are caused by optical geometric asymmetry and can lead to oscillatory and secular changes in attitude. They are computed for one of the largest objects in orbit: Envisat, a defunct satellite with complex geometry. Further to these, simulations of objects spinning in orbit are used to calculate the effect of tumbling on orbital motion. The results show that the effects of nonconservative forces on tumbling objects lead to both periodic and secular variations in their orbital elements. This is contrary to previously popular assumption. Additionally, ideas for utilising modern developments in nanosatellite technology for validation of orbit prediction models are presented and calculations of the Lorentz force and its effect for uncontrolled objects are given. date: 2017-09-28 date_type: published oa_status: green full_text_type: other thesis_class: doctoral_open language: eng thesis_view: UCL_Thesis primo: open primo_central: open_green verified: verified_manual elements_id: 1414623 lyricists_name: Virdee, Hira lyricists_id: HSVIR53 actors_name: Dewerpe, Marie actors_id: MDDEW97 actors_role: owner full_text_status: public pagerange: 1-186 pages: 186 event_title: University College London institution: UCL (University College London) department: Civil, Environmental & Geomatic Engineering thesis_type: Doctoral editors_name: Ziebart, M citation: Virdee, Hira Singh; (2017) Radiation pressure torque and computational attitude modelling of space debris. Doctoral thesis , UCL (University College London). Green open access document_url: https://discovery.ucl.ac.uk/id/eprint/1571169/1/Thesis.pdf